Add PDFWStreamForBuffer. (#386)

Usage : use it when constructing writer, access the resulting `Buffer` 
with PDFWStreamForBuffer.buffer.

Author: PelicanMaster

PDFWStreamForBuffer.js

@@ -0,0 +1,32 @@
+function PDFWStreamForBuffer()
+{
+    this.buffer = null;
+    this.position = 0;
+}
+
+PDFWStreamForBuffer.prototype.write = function(inBytesArray)
+{
+    if(inBytesArray.length > 0)
+    {
+        if(!this.buffer)
+        {
+            this.buffer = Buffer.from(inBytesArray);
+        }
+        else
+        {
+            this.buffer = Buffer.concat([this.buffer, Buffer.from(inBytesArray)]);
+        }
+
+        this.position += inBytesArray.length;
+        return inBytesArray.length;
+    }
+
+    return 0;
+};
+
+PDFWStreamForBuffer.prototype.getCurrentPosition = function()
+{
+    return this.position;
+};
+
+module.exports = PDFWStreamForBuffer;

hummus.js

@@ -27,4 +27,5 @@ hummus.PDFWriter.prototype.triggerDocumentExtensionEvent = function(eventName,ev
 hummus.PDFStreamForResponse = require('./PDFStreamForResponse');
 hummus.PDFWStreamForFile = require('./PDFWStreamForFile');
 hummus.PDFRStreamForFile = require('./PDFRStreamForFile');
-hummus.PDFRStreamForBuffer = require('./PDFRStreamForBuffer');
+hummus.PDFRStreamForBuffer = require('./PDFRStreamForBuffer');
+hummus.PDFWStreamForBuffer = require('./PDFWStreamForBuffer');